ON SOME RARE ARACHNIDS 57 



In the male an entirely different state of things obtains. 

 The sexual aperture is here represented by a central thimble- 

 shaped opening, the apex of which is in front. On each side 

 of this the epigastric and ventral scuta have fused, thus 

 obliterating the rima genitalis in its lateral portions. The 

 point of juncture is marked on each side by the anterior 

 spiracles. The ventral scutum is here short, flat, and is 

 terminated by a curved suture connecting the two posterior 

 spiracles. This is homologous with the posterior border of 

 the ventral scutum of the female, and with the transverse 

 depressed band which occurs in the female of Oonops 

 pulcher. Immediately behind this, and only separated 

 by it from the ventral scutum with which it is fused, 

 is a huge conical scutum, which reaches down beyond 

 the middle of the ventral surface of the abdomen. This 

 may be described as a second ventral scutum, or in terms 

 of human anatomy as an umbilical scutum. It is not repre- 

 sented in the female. 



The arrangement of these scuta will be understood im- 

 mediately if figures 10, 11, and 12 be examined. To make 

 the drawings, most of the protecting and concealing hairs were 

 removed. 



The SPINNERS are six in number, two-jointed, terminal, and 

 arranged in a close bundle. Just above them the integument 

 of the ventral surface of the abdomen is strongly chitinous, and 

 forms a distinct curved ridge. This, no doubt, represents feebly 

 the inframammillary scuta possessed by several allied genera. 

 It varies in development in different individuals, but is always 

 difficult to see. The spinners thus appear to spring from a 

 cup-shaped depression at the posterior end of the body. Their 

 bases seem to be developed in membrane, which also appears 

 to form a sort of pedicle from which they spring. 



At the beginning of October Mr. Bagnall sent me a pair of 

 adult examples of Ischnothyreus velox. He had discovered 

 them in a hot conservatory at Alnwick. A day or two later I 

 paid a visit to Dickson's nurseries at Chester, and had a hunt 



